[PATCH -v6 10/13] tracing: not trace the timecounter_read* in kernel/time/clocksource.c

[Wu Zhangjin <wuzhangjin@gmail.com>]

Some platforms(i.e. MIPS) need these two functions to get the precise
timestamp, we use __arch_notrace(added in the last patch) to annotate
it. By default, __arch_notrace is empty, so, this patch have no
influence to the original functions, but if you really not need to trace
them, just add the following line into the arch specific ftrace.h:

	#define __arch_notrace

If only want to enable it for function graph tracer, add these lines
instead.

	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	#define __arch_notrace
	#endif

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 kernel/time/clocksource.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 5e18c6a..91acdf7 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -30,6 +30,7 @@
 #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
 #include <linux/tick.h>
 #include <linux/kthread.h>
+#include <linux/ftrace.h>
 
 void timecounter_init(struct timecounter *tc,
 		      const struct cyclecounter *cc,
@@ -52,7 +53,7 @@ EXPORT_SYMBOL(timecounter_init);
  * The first call to this function for a new time counter initializes
  * the time tracking and returns an undefined result.
  */
-static u64 timecounter_read_delta(struct timecounter *tc)
+static u64 __arch_notrace timecounter_read_delta(struct timecounter *tc)
 {
 	cycle_t cycle_now, cycle_delta;
 	u64 ns_offset;
@@ -72,7 +73,7 @@ static u64 timecounter_read_delta(struct timecounter *tc)
 	return ns_offset;
 }
 
-u64 timecounter_read(struct timecounter *tc)
+u64 __arch_notrace timecounter_read(struct timecounter *tc)
 {
 	u64 nsec;
 
-- 
1.6.2.1